Because of the frustration US export regulations caused, I wrote
1989 my own DES library, AloDES, in C.
It is a quite fast portable DES library. The package also has an
efficient bignum library. Simple programs to use libraries are also
If you need a bignum DLL for Windows environment, you can get
GNU Copylefted version here. It is
modified for use in Windows ssh, which is a commercial product
of Data Fellows.
Addendum of 2000-10-15
This is quite outdated software package. If you need modern,
supported and royalty free crypto package, I warmly recommend software
found at http://www.openssl.org/. U.S National Institute of Standards and
Technology has announced the nation's proposed new Advanced
Encryption Standard. This finally makes DES officially outdated
as an algorithm. OpenSSL will probably have an AES implementation but
in the meantime other good algorithms in OpenSSL can be used.